(CNN) -- Warning that the safety of the flying public is at stake, two of the nation's best known pilots on Wednesday expressed concern over proposed new rules that would govern pilot duty and rest requirements.

Capt. Chesley "Sully" Sullenberger and First Officer Jeffrey Skiles, who safely landed a disabled US Airways plane in the Hudson River last year, said portions of the government plan would actually increase pilot fatigue.

"For decades, pilot fatigue has been a problem that we have not completely solved," Sullenberger said at a news conference in Washington.

"I'm here to propose that these rules be improved before they're enacted to do what's essential and to protect the safety of the flying public."

The Pilot Flight and Duty Time Rule currently under consideration would consolidate current rest requirements, which vary depending on whether the flight is domestic, international or unscheduled (as with charter flights).

But the Coalition of Airline Pilots Associations, which represents more than 28,000 commercial airline pilots, said several provisions may have a negative impact on flight safety.

The Allied Pilots Association has called parts of the plan "a big step backwards."

Sullenberger and Skiles were particularly critical of a recommendation that would increase pilots' maximum daily flying time from eight to 10 hours.

"We're here to tell you that you cannot reduce pilot fatigue by increasing the amount of time that a pilot is at the controls. The amount of time a pilot can fly must be maintained at the current eight hours a day," Skiles said.

The men also called the government's proposal to provide for a nine-hour minimum rest period for pilots prior to duty -- a one-hour increase over current rules -- as inadequate.

The crew needs about 10 hours in a hotel room to be able to get eight hours of sleep, Sullenberger said.

"The rules that we enact now we must get right. Not only will the people who fly be living under them for decades to come, our passengers will feel the effects of these new rules for decades to come," Sullenberger said.

Over the past 15 years, pilot fatigue has been linked to more than 250 fatalities in air carrier accidents, according to the National Transportation Safety Board.

Pilot fatigue was cited as a chief contributor to the February 2009 crash of Colgan Air Flight 3407. The commuter plane nose-dived into a house near Buffalo, New York, killing all 49 people on the plane and one person on the ground.

The new rules are meant to prevent such tragedies.

In September, Federal Aviation Administration Administrator Randy Babbitt said the proposal "would strengthen the requirement that a pilot has to report fit for duty, fit for the mission that he or she is about to undertake. And that means being fully rested."

Margaret Gilligan, associate administrator for aviation safety with the FAA, said the proposal would provide "a single, scientifically based regulatory approach" to fatigue mitigation.

But Skiles urged for a second look at the legislation.

He called on the FAA and Department of Transportation to review and refine the proposed rules "not with the goal of increasing pilot productivity for the airlines, but with an eye solely focused on the safety of the traveling public."

Meanwhile, Sullenberger urged air travelers to let the government know how they feel about the changes. People can send comments via Regulations.gov.